JP4595487B2 - Deposition method of gas barrier silicon oxide thin film by CVD method - Google Patents

Description

  The present invention provides a gas barrier silicon oxide thin film by CVD (chemical vapor deposition) on the surface of a three-dimensional hollow container such as a plastic bottle, a plastic cup, a plastic tray, a paper container, a paper cup, a paper tray, and other hollow plastic molded products. The present invention relates to a film forming method for forming a film.

  In recent years, attempts have been made to improve the gas barrier property, water vapor barrier property, surface wettability, and the like of a container by forming a thin film on the surface of a three-dimensional hollow container such as a plastic container. As one of the methods for forming these functional thin films, there is a method of forming a thin film on the surface of a container by using a chemical reaction of a process gas by a plasma assisted CVD method. For example, as shown in Patent Document 1, a method of forming a film by installing a container between a hollow external electrode that is substantially similar to the outer shape of the container and an internal electrode that is substantially similar to the outer shape of the container, As disclosed in Patent Document 2, a method of forming a film by arranging both the external electrode and the internal electrode at a substantially constant distance from the surface of the container is used.

  When a silicon oxide thin film is formed by such a CVD method, a mixed gas of an organic silicone gas and a gas having an oxidizing power such as oxygen is generally used as a raw material. The properties of the silicon oxide thin film to be formed can be variously changed by changing the flow rate of the gas having a difference and the mixing ratio thereof. For example, in the film forming method described in Patent Document 3, a thin film having a high barrier property can be obtained if the mixing ratio of the organic silicone gas and the gas having oxidizing power is optimal. By changing the supply amount of the organic silicone gas and the gas having oxidizing power so as to change at least including the range, a thin film having excellent gas barrier properties can be obtained easily and stably.

However, there is a limit to the level of gas barrier properties of the thin film obtained by simply changing the mixing ratio of the organic silicone compound gas and the gas having oxidizing power in the state described in Patent Document 3, and the film formation is limited. There was a problem that it took a long time.
JP-A-8-53117 JP-A-8-175528 JP 2004-124134 A

  The present invention has been made to solve the above-mentioned problems of the prior art, and a film forming method capable of forming a silicon oxide thin film having excellent gas barrier properties stably and in a short time using a CVD method. The purpose is to provide.

The present invention solves this problem, and the invention according to claim 1 is a method for forming a silicon oxide thin film on the surface of a container by a CVD method using at least an organosilicon compound gas and a gas having an oxidizing power. In this case, the flow rate ratio between the organosilicon compound gas to be supplied and the gas having oxidizing power is repeatedly increased / decreased at a rate of at least once / second while including the range of the flow rate ratio capable of forming a gas barrier silicon oxide thin film having a good flow rate. Thus, the film formation method of the gas barrier silicon oxide thin film by the CVD method is characterized in that the film formation is performed while increasing or decreasing the supply flow rate of the organosilicon compound gas.

According to a second aspect of the present invention, there is provided a gas barrier silicon oxide thin film formed by the CVD method according to the first aspect, wherein the flow rate ratio between the organosilicon compound gas and the gas having oxidizing power is good. The supply flow rate of the organosilicon compound gas is increased or decreased so as to increase or decrease three times or more while including the range of the flow rate ratio at which the thin film can be formed .

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Furthermore, the invention described in claim 3 is the gas barrier silicon oxide thin film deposition method according to claim 1 or 2 , wherein the organosilicon compound is hexamethyldisiloxane and the gas having oxidizing power is oxygen. The flow ratio of these gases is 1:10 to 0.01: 10
The film formation is performed by increasing / decreasing the supply amount of the organosilicon compound gas so as to increase / decrease repeatedly while including the range.

  According to the film formation method of the gas barrier silicon oxide thin film by the CVD method of the present invention, a silicon oxide thin film having excellent gas barrier properties can be stably and quickly formed on the surface of the container. A container having a silicon oxide thin film excellent in gas barrier properties for containing an object can be manufactured and provided at low cost.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration explanatory view showing an example of a film forming apparatus used when the film forming method of the present invention is carried out.

  This film forming apparatus includes an external electrode 2 made of a conductive material having a cylindrical space that can accommodate a container 1 in which a thin film is to be formed, and a canopy 3 installed at one open end thereof. A film forming chamber is configured by being integrated with a bottom cover 5 provided at the other opening end and provided with an exhaust port 4 at a part thereof. The film forming chamber is provided with a vacuum pump (not shown) through an exhaust port 4 provided in a part of the bottom cover 5 in order to make the inside of the film forming chamber vacuum. In addition, a container holder 6 made of an insulator is disposed in the film forming chamber in order to place the container 1 for forming a thin film on the surface at an appropriate position in the vacuum chamber. On the other hand, a gas introduction pipe 7 is inserted into the film forming chamber from the bottom lid 5 and the inside of the container 1 in which the source gas is set in the film forming chamber from the source gas discharge port 8 at the tip thereof. To be supplied.

In the case of forming a gas barrier silicon oxide thin film on the inner surface of the container using the film forming apparatus having such a configuration, first, a vacuum pump is operated to depressurize the film forming chamber to a certain degree of vacuum. Next, the raw material gas from the gas introduction pipe 8 to the high-frequency power is applied to the external electrodes 2 in a state in which the fed by the gas introduction pipe 7 Rikyo, the raw material gas present in the container 1 is plasma, the inner surface of the container 1 A thin film of silicon oxide is formed.

  In the present invention, when a silicon oxide thin film is formed on the surface of a container by a CVD method using at least two kinds of gases, that is, an organic silicone compound gas and an oxidizing power gas, The film formation is performed while increasing / decreasing the gas supply flow rate so as to repeatedly increase / decrease while including the range of the flow rate ratio in which the gas barrier silicon oxide thin film having a good gas flow rate ratio can be formed.

  In such a state, the film is formed while increasing / decreasing the supply amount of the organosilicon compound gas and the gas having oxidizing power, thereby supplying the gas at a flow rate ratio capable of forming a silicon oxide thin film having a good gas barrier property. As a result, the gas barrier property of the entire silicon oxide thin film becomes stable, and the optimum mixing ratio range is obtained. As compared with the case where the film is formed by changing the supply amount of the organic silicone gas and the gas having an oxidizing power so as to include, it is possible to stably obtain a silicon oxide thin film having excellent gas barrier properties.

  At this time, the flow rate ratio between the organosilicon compound gas to be supplied and the gas having an oxidizing power is repeatedly increased and decreased while including the range of the flow rate ratio in which the gas barrier silicon oxide thin film is formed. The number of times to increase or decrease the supply flow rate is preferably at least 3 times. If it is less than 3 times, the effect of improving the gas barrier property of the obtained silicon oxide thin film is small. In addition, the rate of the flow rate ratio to be increased or decreased is desirably 1 time / second or more, and if it is less than that, the effect of shortening the film formation time is small.

  In addition, the supply flow ratio of the organic silicone compound gas capable of forming a good gas barrier silicon oxide thin film and the gas having oxidizing power varies depending on the type of raw material gas used, for example, the organic silicone compound is hexamethyldisiloxane, When the gas having oxidizing power is oxygen, it is in the range of 1:10 to 0.01: 10.

  Examples of the organic silicone compound include 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, vinyltrimethylsilane, methyltrimethoxysilane, hexamethyldisilane, methylsilane, dimethylsilane, trimethylsilane, and diethylsilane. Propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, octamethylcyclotetrasiloxane and the like. Of these, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, and octamethylcyclotetrasiloxane are particularly preferably used. However, it is not limited to these and aminosilane, silazane, etc. can also be used. Examples of the gas having oxidizing power include, but are not limited to, oxygen, carbon monoxide, carbon dioxide, ozone, and the like.

  However, from the viewpoint of safety, price, and availability, the organosilicon compound is hexamethyldisiloxane, oxygen is preferred as the gas having oxidizing power, and these gases can be used to form a good gas barrier thin film. It is desirable to perform film formation by supplying the liquid so as to increase or decrease repeatedly at least three times including the range of 1:10 to 0.01: 10. However, for example, to improve the adhesion between the container for forming the thin film and the gas barrier thin film, or to prevent the gas barrier property of the thin film from deteriorating even when the container is deformed, When it is necessary to provide carbon-rich silicon oxide portions on both sides, the flow rate should be increased so that the ratio of the organosilicon compound gas is increased at the beginning and end of the film forming process as shown in FIG. You may adjust and supply to. Examples of the present invention will be described below.

<Example 1>
Using a film forming apparatus as shown in FIG. 1, a silicon oxide thin film was formed on the inner surface of a polyethylene terephthalate container having a capacity of 500 ml as follows. The organosilicon compound gas used was hexamethyldisiloxane, and the gas having an oxidizing power was oxygen.

In forming the film, first, after the inside of the film forming chamber was evacuated, as shown in the profile of Table 1, the flow rate of the organic silicone gas and the initial flow rate of the oxygen gas were set to 10 (sccm): 100 (sccm), After 1 second from the start of film formation, the flow rate of the organic silicone gas and the flow rate of oxygen gas are set to 1 ( sccm): 100 (sccm), and thereafter , every time 1 second passes , 10: 100, 1: 100 Film formation was performed by changing the gas flow rates of 10: 100 and 1: 100. At this time, the applied high frequency power was 400 watts.

And the oxygen permeability of the container in which the silicon oxide thin film was formed was measured using MOCON OXITRAN manufactured by MOCON. Table 1 shows the results and changes in the flow rates of the organosilicon compound gas and oxygen during film formation .

<Comparative Example 1>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 2 seconds as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Example 2>
As shown in Table 1, the conditions of the polyethylene terephthalate container were changed under the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 0.5 seconds as shown in Table 1. A silicon oxide thin film was formed on the inner surface. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Example 3>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 1 second as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Example 4>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 1 second as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Example 5>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 1 second as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Comparative Example 2>
Polyethylene terephthalate under the same conditions as in Example 1 except that the flow rate of the organosilicon compound gas and the flow rate of oxygen were changed every 1 second as shown in Table 1 and the film was formed over 3 seconds. A silicon oxide thin film was formed on the inner surface of the container. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Comparative Example 3>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 1 second as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Comparative Example 4>
The inner surface of the polyethylene terephthalate container was subjected to the same conditions as in Example 1 except that the film was formed by changing the flow rate of the organosilicon compound gas and the flow rate of oxygen every 1 second as shown in Table 1. A silicon oxide thin film was formed. Table 1 shows the oxygen permeability of the container in which the silicon oxide thin film was formed and the changes in the flow rates of the organic silicone gas and oxygen gas during the film formation .

<Comparative Example 5>
Using a film forming apparatus as shown in FIG. 1, a silicon oxide thin film was formed on the inner surface of a polyethylene terephthalate container having a capacity of 500 ml as follows. The organosilicon compound gas used was hexamethyldisiloxane, and the gas having an oxidizing power was oxygen.

In the film formation, first, after the inside of the film formation chamber was evacuated, as shown in the profile of Table 1, the initial flow rate of the organosilicon compound gas flow rate and the oxygen gas flow rate at the start of film formation was 10 ( sccm): 100 (sccm) was changed to 1 (sccm): 100 (sccm) after 5 seconds under the same conditions as in Example 1 except that it was changed to Example 10 for comparison. Such film formation was performed .

<Comparative Example 6>
The flow rate of the organic silicone compound gas and the flow rate of the oxygen gas at the start of film formation was 1 (sccm): 100 (sccm) after 5 seconds when the initial values were 5 (sccm): 100 (sccm), respectively. Except for the above, film formation according to Example 11 for comparison was performed under the same conditions as in Example 1 .

<Comparative Example 7>
Except that the flow rate of the organic silicone compound gas and the flow rate of oxygen gas at the start of film formation are the same as the initial values until 1 second elapses, and then 1 (sccm): 100 (sccm) after 4 seconds. Under the same conditions as in Example 1, film formation according to Example 12 for comparison was performed.

It is a schematic explanatory drawing which shows an example of the structure in the film-forming apparatus used for the film-forming method of the gas-barrier silicon oxide thin film by DVD method of this invention. It is explanatory drawing which shows the example of the change of the flow rate ratio of the organosilicon compound gas and the gas which has oxidizing power comprised in the film-forming method of the gas-barrier silicon oxide thin film by DVD method of this invention. It is explanatory drawing which shows the example of the other change of the flow rate ratio of the organosilicon compound gas and the gas which has oxidizing power comprised in the film-forming method of the gas-barrier silicon oxide thin film by DVD method of this invention.

DESCRIPTION OF SYMBOLS 1 ... Container 2 ... External electrode 3 ... Canopy 4 ... Exhaust port 5 ... Bottom cover 6 ... Container holding part 7 ... Gas introduction pipe 8 ... Gas discharge port

Claims (3)

A gas barrier having a good flow rate ratio between an organosilicon compound gas to be supplied and a gas having an oxidizing power in a method of forming a silicon oxide thin film on the surface of a container by a CVD method using at least an organosilicon compound gas and a gas having an oxidizing power. Forming the film while increasing / decreasing the supply flow rate of the organosilicon compound gas so as to repeatedly increase / decrease at a rate of at least once / second while including the range of the flow rate ratio capable of forming a conductive silicon oxide thin film. A film forming method of a gas barrier silicon oxide thin film by a CVD method. The supply flow rate of the organosilicon compound gas is increased or decreased three times or more while including the range of the flow rate ratio in which the silicon oxide thin film having a good gas barrier property can be formed. 2. The method for forming a gas barrier silicon oxide thin film by CVD according to claim 1, wherein the number is increased or decreased. The organic silicone compound gas is hexamethyldisiloxane, the gas having oxidizing power is oxygen, and the organic silicone compound gas is repeatedly increased or decreased while including a range in which the flow ratio of these gases is 1:10 to 0.01: 10. 3. The method for forming a gas barrier silicon oxide thin film by a CVD method according to claim 1, wherein the film is formed by increasing / decreasing the amount of supply.

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